Multiple-metal complex-containing compound and metal complex, and manufacture methods therefor, and exhaust gas purification catalyst manufacture method using the same

ABSTRACT

A multiple-metal complex-containing compound in accordance with an embodiment has a plurality of metal complexes in each of which a ligand is coordinated to one metal atom or a plurality of metal atoms of the same kind. The plurality of metal complexes are bound to each other via a polydentate ligand that substitutes partially the ligands of the two or more metal complexes, and have 2 to 1000 metal atoms.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a multiple-metal complex-containing compoundand a metal complex, and manufacture method therefor as well as anexhaust gas purification catalyst manufacture method using the same. Inparticular, the invention relates to a method of manufacturing a metalparticle having a controlled cluster size through the use of themultiple-metal complex-containing compound and the metal complex.

2. Description of the Related Art

A size-controlled metal cluster is different from a bulk metal inchemical characteristics, such as catalytic activity and the like, andphysical characteristics, such as magnetism and the like.

In order to efficiently utilize the peculiar characteristics of themetal cluster, a method for easily synthesizing a size-controlledcluster in large amount is needed. A known method for obtaining such acluster is a method in which (i) clusters of various sizes are producedby causing a metal target to evaporate in vacuum, and (ii) thethus-obtained clusters are separated according to cluster sizes throughthe use of the principle of the mass spectrum. However, this method isnot able to easily synthesize a cluster in large amount.

The peculiar characteristics of the cluster is disclosed in, forexample, “Adsorption and Reaction of Methanol Molecule on Nickel ClusterIons, Ni_(n) ⁺ (n=3-11)”, M. Ichihashi, T. Hanmura, R. T. Yadav and T.Kondow, J. Phys. Chem. A, 104, 11885 (2000) (non-patent document). Thisdocument discloses that the reactivity between methane molecules andplatinum catalyst in the gas phase is greatly affected by the platinumcluster size; and that there exists a particular platinum cluster sizethat is optimal for the reaction, for example, as shown in FIG. 1.

Examples of utilization of the catalytic performance of a noble metalinclude purification of exhaust gas discharged from an internalcombustion engine, such as an automotive engine or the like. At the timeof the purification of exhaust gas, exhaust gas components, such ascarbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO_(X)), etc.,are converted into carbon dioxide, nitrogen and oxygen by catalystcomponents whose main component is a noble metal such as platinum (Pt),rhodium (Rh), palladium (Pd), iridium (Ir), etc. Generally, the catalystcomponent that is a noble metal is supported on a support made of anoxide, such as alumina or the like, in order to enlarge the contact areafor exhaust gas and the catalyst component.

In order to support a noble metal on the oxide support; the oxidesupport is impregnated with a solution of a nitric acid salt of a noblemetal or a noble metal complex having one noble metal atom so that thenoble metal compound is dispersed on surfaces of the oxide support, andthen the support impregnated with the solution is dried and fired. Inthis method, however, it is not easy to control the size and the numberof atoms of the noble metal cluster.

With regard to such catalysts for exhaust gas purification, too, thesupporting of a noble metal in the form of clusters has been proposed inorder to further improve the exhaust gas purification capability. Forexample, Japanese Patent Application Publication No. JP-A-11-285644discloses a technology in which a catalytic metal is supported in theform of ultrafine particle directly on a support through the use of ametal cluster complex that has a carbonyl group as a ligand.

Furthermore, Japanese Patent Application Publication No.JP-A-2003-181288 discloses a technology in which a noble metal catalysthaving a controlled cluster size is manufactured by introducing a noblemetal into pores of a hollow carbon material, such as carbon nanotube orthe like, and fixing the carbon material with the noble metal introducedtherein to an oxide support, and then firing it.

Still further, Japanese Patent Application Publication No. JP-A-9-253490discloses a technology in which a metal cluster made up of an alloy ofrhodium and platinum dissolved in the solid state is obtained by addinga reductant: to a solution containing rhodium ions and platinum ions.

With regard to the metal complex, obtaining a polymer having an infinitenumber of metal atoms through the use of a polydentate ligand is known.For example, Japanese Patent Application Publication No.JP-A-2000-109485 discloses a technology for obtaining a dicarboxylicacid metal complex polymer having a giant three-dimensional structurethrough the use of a dicarboxylic acid.

SUMMARY OF THE INVENTION

The invention provides a novel multiple-metal complex-containingcompound that allows easy synthesis of large amount of a size-controlledcluster, and a metal complex that can be used for the synthesis of thecompound. The invention also provides methods for manufacturing themultiple-metal complex-containing compound and the complex, and methodsof using the multiple-metal complex-containing compound and the complex.

A first aspect of the invention relates to a multiple-metalcomplex-containing compound including two or more metal complexes ineach of which a ligand is coordinated to one metal atom or a pluralityof metal atoms of the same kind, wherein the two or more metal complexesare bound to each other via a polydentate ligand that substitutespartially the ligands of the two or more metal complexes, and have 2 to1000 metal atoms.

According to the foregoing aspect, if the ligands are removed from themultiple-metal complex-containing compound by firing or the like, ametal or metal oxide cluster, having the same number of metal atoms ascontained in the compound can be obtained.

A second aspect of the invention relates to a manufacture method for ametal or metal oxide cluster that has 2 to 1000 metal atoms, whichincludes (a) providing a solution containing the multiple-metalcomplex-containing compound of the invention, and (b) drying and firingthe solution.

A third aspect of the invention relates to a manufacture method for amultiple-metal complex-containing compound, which includes: providing ametal complex; providing a polydentate ligand or a polydentate ligandsource; and dissolving the metal complex and the polydentate ligand orthe polydentate ligand source in a solvent.

According to the foregoing aspect, a multiple-metal complex-containingcompound having a controlled number of metal atoms can be obtained bysubstituting at least only partially the ligands coordinated in themetal complexes, with a polydentate ligand. It is to be noted hereinthat the term “polydentate ligand source or ligand source” in thisspecification means a polydentate ligand or a compound (precursor) thatprovides or a ligand when dissolved in a solvent.

A fourth aspect of the invention relates to a metal complex in whichligands are coordinated to one metal atom or a plurality of metal atomsof the same kind, and at least one of the ligands has an uncoordinatedfunctional group that is not coordinated to a metal atom and that isselected from the group consisting of: —COOH, —COOR⁸, —CR⁸R⁹—OH,—NR⁸{C(═O)R⁹}, —NR⁸R⁹, —CR⁸═N—R⁹, —CO—R⁸, —PR⁸R⁹, —P(═O)R⁸R⁹,—P(OR⁸)(OR⁹), —S(═O)₂R⁸, —S⁺(—O⁻)R⁸, —SR⁸, —CR⁸R⁹—SH, —CR⁸R⁹—SR¹⁰, and—CR⁸═R⁹R¹⁰ (R⁸ to R¹⁰ each independently are hydrogen or a monovalentorganic group).

According to the foregoing aspect, the characteristics of a functionalgroup that is not coordinated to a metal atom can be utilized.Concretely, through the use of such functional groups, it is possible tostably adsorb the metal complex to a substrate, bind metal complexes toeach other, bind the metal complex and another compound, etc.

A fifth aspect of the invention relates to a manufacture method for anexhaust gas purification catalyst, which includes: providing a solutioncontaining the metal complex according to the foregoing aspects;impregnating a catalyst support with the solution; and drying and firingthe solution.

According to this aspect, a metal complex is adsorbed to a catalystsupport due to the affinity between a functional group not coordinatedto a metal atom and the catalyst support, so that when the metal complexis fired or the like, the metal contained in the metal complex can besupported on the catalyst support with high degree of dispersion.

A sixth aspect of the invention relates to a manufacture method for amultiple-metal complex-containing compound, which includes: providing ametal complex that has a ligand that has an uncoordinated carbon-carbondouble bond; and dissolving the metal complex in a solvent andsubstituting an alkylidene group of an uncoordinated carbon-carbondouble bond through a cross-metathesis reaction of the carbon-carbondouble bond.

According to the foregoing aspect, a multiple-metal complex-containingcompound can be manufactured from a metal complex that has anuncoordinated carbon-carbon double bond, through the cross-metathesisreaction of a carbon-carbon double bond (olefin).

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and/or further objects, features and advantages of theinvention will become more apparent from the following description ofpreferred embodiment with reference to the accompanying drawings; inwhich like numerals are used to represent like elements and wherein:

FIG. 1 is a graph showing a relationship between the Pt cluster size andthe reactivity extracted from the aforementioned non-patent document;

FIG. 2 shows a TEM photograph in which the appearance of Pt on MgOprepared by a method of Comparative Example was observed;

FIG. 3 shows a scheme for synthesizing a compound in accordance withExample 1;

FIG. 4 shows a TEM photograph in which the appearance of Pt on MgOprepared by a method of Example 1 was observed;

FIG. 5 shows a scheme for synthesizing a compound in accordance withExample 2;

FIG. 6 shows a scheme for synthesizing the compound in accordance withExample 2;

FIG. 7 shows a TEM photograph in which the appearance of Pt on MgOprepared by a method of Example 2 was observed; and

FIG. 8 shows a scheme for synthesizing a compound in accordance withExample 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, the present invention will be described inmore detail in terms of exemplary embodiments.

(Multiple-Metal Complex-Containing Compound)

A multiple-metal complex-containing compound in accordance with anembodiment of the invention has a plurality of metal complexes in eachof which a ligand is coordinated to one metal atom or a plurality ofmetal atoms of the same kind. In this compound, a plurality of metalcomplexes are bound to each other via a polydentate ligand thatsubstitutes partially the ligands, and have 2 to 1000 metal atoms. Thenumber of the metal atoms may be 2 to 100, for example, 2 to 50, or 2 to20, or 2 to 10.

(Ligand of a Metal Complex)

The ligands of the metal complexes of the multiple-metalcomplex-containing compound in accordance with the embodiment can bearbitrarily selected, taking into consideration the properties of themultiple-metal complex-containing compound obtained, the sterichindrance between metal complexes to be bound, etc. The ligand may beeither a unidentate ligand or a polydentate ligand such as a chelateligand.

This ligand may be a hydrogen group bound with one functional groupselected from the group of functional groups mentioned below, or anorganic group bound with one or more functional groups selected from thegroup of functional groups mentioned below, particularly an organicgroup bound with one or more functional groups of the same kind selectedfrom the group consisting of: —COO⁻ (carboxy group), —CR¹R²—O⁻ (alkoxygroup), —NR¹⁻ (amide group), —NR¹R² (amine group), —CR¹═N—R² (iminegroup), —CO—R¹ (carbonyl group), —PR¹R² (phosphine group), —P(═O)R¹R²(phosphine oxide group), —P(OR¹)(OR²) (phosphite group); —S(═O)₂R¹(sulfone group), —S⁺(—O⁻)R¹ (sulfoxide group), —SR¹ (sulfide group), and—CR¹R²—S⁻ (thiolato group); and particularly —COO⁻ (carboxy group),—CR¹R²—O⁻ (alkoxy group), —NR¹⁻ (amide group), and —NR¹R² (amine group)(R¹ and R² each independently are hydrogen or a monovalent organicgroup).

The organic group bound with a functional group may be a substituted ornon-substituted hydrocarbon group, particularly a substituted ornon-substituted hydrocarbon group of C₁ to C₃₀ (i.e., whose carbon atomnumber is 1 to 30; this will be applied in the following description aswell), that may have a hetroatom, an ether bond or an ester bond. Inparticular, this organic group may be an alkyl group, an alkenyl group,an alkynyl group, an aryl group, an aralkyl group or a monovalentalicyclic group of C₁ to C₃₀, particularly C₁ to C₁₀. More particularly,this organic group may be an alkyl group, an alkenyl group, an alkynylgroup of C₁ to C₅, particularly C₁ to C₃.

R¹ and R² may each independently be hydrogen, or a substituted ornon-substituted hydrocarbon group, particularly a substituted ornon-substituted hydrocarbon group of C₁ to C₃₀, that may have ahetroatom, an ether bond or an ester bond. Particularly, R¹ and R² maybe hydrogen, or an alkyl group, an alkenyl group, an alkynyl group, anaryl group, an aralkyl group or a monovalent alicyclic group of C₁ toC₃₀, particularly C₁ to C₁₀. More particularly, R¹ and R² may behydrogen, or an alkyl group, an alkenyl group or an alkynyl group of C₁to C₅, particularly C₁ to C₃.

Examples of the ligand of the metal complex include a carboxylic acidligand (R—COO⁻), an alkoxy ligand (R—CR¹R²—O⁻), an amide ligand(R—NR¹⁻), an amine ligand (R—NR¹R²), an imine ligand (R—CR¹═N—R²), acarbonyl ligand (R—CO—R¹), a phosphine ligand (R—PR¹R²), a phosphineoxide ligand (R—P(═O)R¹R²), a phosphite ligand (R—P(OR¹)(OR²)), asulfone ligand (R—S(═O)₂R¹), a sulfoxide ligand (R—S⁺(—O⁻)R¹), a sulfideligand (R—SR¹), and a thiolato ligand (R—CR¹R²—S⁻) (R is hydrogen or anorganic group, and R¹ and R² areas mentioned above).

Concrete examples of the carboxylic acid ligand include a formic acid(formato) ligand, an acetic acid (acetato) ligand, a propionic acid(propionato) ligand, and an ethylenediaminetetraacetic acid ligand.

Concrete examples of the alkoxy ligand include a methanol (methoxy)ligand, an ethanol (ethoxy) ligand, a propanol (propoxy) ligand, abutanol (butoxy) ligand, a pentanol (pentoxy) ligand, a dodecanol(dodecyl oxy) ligand, and a phenol (phenoxy) ligand.

Concrete examples of the amide ligand include a dimethyl amide ligand, adiethyl amide ligand, a di-n-propyl amide ligand, a diisopropyl amideligand, a di-n-butyl amide ligand, a di-t-butyl amide ligand, and anicotine amide.

Concrete examples of the amine ligand include methyl amine, ethyl amine,methyl ethyl amine, trimethyl amine, triethyl amine, ethylene diamine,tributyl amine, hexamethylene diamine, aniline, ethylene diamine,propylene diamine, trimethylene diamine, diethylene triamine,triethylene tetraamine, tris(2-aminoethyl)amine, ethanol amine,triethanol amine, ethanol amine, triethanol amine, diethanol amine,trimethylene diamine, piperidine, triethylene tetramine, and triethylenediamine.

Concrete examples of the imine ligand include diimine, ethyleneimine,propyleneimine, hexamethyleneimine, benzophenoneimine, methyl ethylketone imine, pyridine, pyrazole, imidazole, and benzoimidazole.

Concrete examples of the carbonyl ligand include carbon monoxide,acetone, benzophenone, acetyl acetone, acenaphthoquinone,hexafluoroacetyl acetone, benzoyl acetone, trifluoroacetyl acetone, anddibenzoyl methane.

Concrete examples of the phosphine ligand include phosphorus hydride,methyl phosphine, dimethyl phosphine, trimethyl phosphine, anddiphosphine.

Concrete examples of the phosphine oxide ligand include tributylphosphine oxide, triphenyl phosphine oxide, and tri-n-octyl phosphineoxide.

Concrete examples of the phosphite ligand include triphenyl phosphite,tritolyl phosphite, tributyl phosphite, and triethyl phosphite.

Concrete examples of the sulfone ligand include hydrogen sulfide,dimethyl sulfone, and dibutyl sulfone.

Concrete examples of the sulfoxide ligand include a dimethyl sulfoxideligand, and a dibutyl sulfoxide ligand.

Concrete examples of the sulfide ligand include ethyl sulfide, butylsulfide, etc.

Concrete examples of the thiolato ligand include a methanethiolatoligand, and a benzenethiolato ligand.

(Polydentate Ligand)

As the polydentate ligand that substitutes partially the ligands of aplurality metal complexes and that binds the metal complexes to eachother, an arbitrary polydentate ligand that can play the aforementionedrole may be used. It is considered preferable that the polydentateligand have a certain length in order to avoid destabilization of themultiple-metal complex-containing compound due to the steric hindrancebetween metal complexes. Particularly, in the case where themultiple-metal complex-containing compound in accordance with theembodiment of the invention is subjected to firing or the like so as toobtain a cluster that has the same number of metal atoms as contained inthis compound, an excessively great length of the polydentate ligand maypossibly make it difficult to obtain a single kind of cluster from thecompound.

The polydentate ligand that substitutes partially the ligands of themetal complexes may be represented by the following formula:

(L¹)-R³-(L²)

(where R³ is a bond or a bivalent organic group, and L¹ and L² areeither the same or different functional groups selected from the groupconstituting of: —COO⁻ (carboxy group), —CR⁴R⁵—O⁻ (alkoxy group), —NR⁴—(amide group), —NR⁴R⁵ (amine group), —CR⁴═N—R⁵ (imine group), —CO—R⁴(carbonyl group), —PR⁴R⁵ (phosphine group), —P(═O)R⁴R⁵ (phosphine oxidegroup), —P(OR⁴)(OR⁵) (phosphite group), —S(═O)₂R⁴ (sulfone group),—S⁺(—O⁻)R⁴ (sulfoxide group), —SR⁴ (sulfide group), and —CR¹R⁴—S⁻(thiolato group) (R⁴ and R⁵ each independently are hydrogen or amonovalent organic group)).

In particular, L¹ and L² may represent the same functional groupselected from the group consisting of: —COO⁻ (carboxy group), —CR⁴R⁵—O⁻(alkoxy group), —NR⁴— (amide group), and —NR⁴R⁵ (amine group) (R⁴ and R⁵each independently are hydrogen or a monovalent organic group).

R³ may be a bond, or a substituted or non-substituted bivalenthydrocarbon group, particularly a substituted or non-substitutedbivalent hydrocarbon group of C₁ to C₃₀, that may have a heteroatom, anether bond or an ester bond. Particularly, R³ may be an alkylene group,an alkenylene group, an alkynylene group, an arylene group, an aralkylengroup or a bivalent alicyclic group of C₁ to C₃₀ and, particularly C₁ toC₁₀.

R⁴ and R⁵ may be organic groups mentioned in conjunction with R² and R².

(Combination of a Polydentate Ligand and a Ligand of a Metal Complex)

The ligands of the metal complexes, and the polydentate ligandsubstituting partially the ligands of the metal complexes may have thesame functional group. For example, the ligands of the metal complexesand the polydentate ligand may each have a carboxy group, an alkoxygroup, an amide group, or an amine group.

(Metal that Becomes a Nucleus of a Metal Complex)

The metal that becomes a nucleus of the metal complex may be either amain group metal or a transition metal. This metal may be particularly atransition metal, and more particularly fourth to eleventh grouptransition metals, for example, a metal selected from the groupconsisting of titanium, vanadium, chromium, manganese, iron, cobalt,nickel, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium,palladium, silver, hafnium, tantalum, tungsten, rhenium, osmium,iridium, platinum, and gold.

Furthermore, in the case where a catalyst is provided through the use ofa multiple-metal complex-containing compound in accordance with theembodiment, the metal to be used may be a metal beneficial for the useof the catalyst, for example, elements of the iron family (iron, cobalt,nickel), copper, platinum group elements (ruthenium, rhodium, palladium,osmium, iridium, and platinum), gold, or silver.

(Metal Complex)

As for the multiple-metal complex-containing compound in accordance withthe embodiment, the metal complexes each may be an arbitrary metalcomplex in which a ligand is coordinated to one metal atom or aplurality of metal atoms of the same kind. That is, the metal complexmay be a polynuclear complex, for example, a complex that has 2 to 10metal atoms, particularly 2 to 5 metal atoms.

This metal complex may be an arbitrary metal complex. Concrete examplesof the metal complex include [Pt₄(CH₃COO)₈], [Pt(acac)₂] (“acac” is anacetyl acetonato ligand), [Pt(CH₃CH₂NH₂)₄]Cl₂, [Rh₂(C₆H₅COO)₄],[Rh₂(CH₃COO)₄], [Rh₂(OOCC₆H₄COO)₂], [Pd(acac)₂], [Ni(acac)₂],[Cu(C₁₁H₂₃COO)₂]₂, [Cu₂(OOCC₆H₄COO)₂], [Cu₂(OOCC₆H₄CH₃)₄],[Mo₂(OOCC₆H₄COO)₂], [Mo₂(CH₃COO)₄], and[N(n-C₄H₉)₄][Fe^(II)Fe^(III)(ox)₃] (“ox” is an oxalic acid ligand).

(Form in which the Multiple-Metal Complex-Containing Compound hasCarboxylic Acid Ligands)

The multiple-metal complex-containing compound in accordance with theembodiment may be in a fowl in which the metal complexes are metalcomplexes that have carboxylic acid ligands, particularly acetic acidligands, for example, octaacetatotetraplatinum ([Pt(μ-CH₃COO)₈]), and inwhich the polydentate ligand substituting partially the ligands of themetal complexes is a dicarboxylic acid ligand.

The dicarboxylic acid ligand may be represented by the followingformula:

⁻OOC—R⁶—COO⁻

(R⁶ is an alkylene group, an alkenylene group, an alkynylene group, anarylene group, an aralkylen group or a bivalent alicyclic group of C₁ toC₃₀ and, particularly, C₁ to C₁₀).

R⁶ may be selected from the group consisting of p-phenylene groups, andalkenylene groups represented by the following formula:

—(CH₂)_(n)C═C(CH₂)_(n)—

(n is an integer of 1 to 5).

(Form in which the Metal Complexes are Octaacetatotetraplatinum)

The multiple-metal complex-containing compound in accordance with theembodiment may be represented by the following formula:

(R⁷ is an alkylene group, an alkenylene group, an alkynylene group, anarylene group, an aralkylen group or a bivalent alicyclic group of C₁ toC₃₀, particularly C₁ to C₁₀).

R⁷ may be selected from the group consisting of p-phenylene groups, andalkenylene groups represented by the following formula:

—(CH₂)_(n)C═C(CH₂)_(n)—

(n is an integer of 1 to 5).

(Manufacture Method for a Metal or Metal Oxide Cluster)

In the manufacture method for a metal or metal oxide cluster having 2 to1000 metal atoms in accordance with the embodiment, (a) a solutioncontaining the multiple-metal complex-containing compound of theinvention is provided, and (b) the solution is dried and fired.

The drying and firing of the solution containing the multiple-metalcomplex-containing compound can be performed in a condition of atemperature and a time that are sufficient to obtain a metal or metaloxide cluster. For example, the drying may be performed at a temperatureof 120 to 250° C. for 1 to 2 hours, and then the firing may be performedat a temperature of 400 to 600° C. for 1 to 3 hours. The solvent of thesolution to be used in this method may be an arbitrary solvent that iscapable of stably maintaining the multiple-metal complex-containingcompound of the invention, for example, an aqueous solvent, or anorganic solvent such as dichloroethane, or the like.

This method may further include impregnating a porous support with thesolution before drying and firing the solution in the step (b).

In the case where a catalyst, particularly, an exhaust gas purificationcatalyst, is to be manufactured by using this method, the porous supportto be used may be a porous metal oxide support, for example, a porousmetal oxide support selected from the group consisting of alumina,ceria, zirconia, silica, titania, and their combinations.

(Manufacture Method for a Multiple-Metal Complex-Containing Compound ofthe Invention)

In the manufacture method for the multiple-metal complex-containingcompound in accordance with the embodiment, (a) a metal complex isprovided, and (b) a polydentate ligand or a polydentate ligand source isprovided, and (c) the metal complex and the polydentate ligand or thepolydentate ligand source are mixed in a solvent.

The polydentate ligand to be used in this method is selected so that theselected polydentate ligand can substitute ligands coordinated in themetal complex for use as a raw material. Therefore, in general, it ispossible to use a polydentate ligand that has stronger coordinatingpower than the ligands coordinated in the metal complex for use as a rawmaterial, particularly a polydentate ligand that has strongercoordinating power than the ligands coordinated in the metal complex foruse as a raw material and that has the same number of functional groupsas the ligands.

The polydentate ligand may be used in relatively large amount in orderto accelerate the substitution of the ligands of the metal complex withthe polydentate ligand. However, the amount of the polydentate ligand tobe used in this method may be less than the amount that is needed inorder to substitute entirely the ligands coordinated in the metalcomplex. The amount of the polydentate ligand to be used in this methodmay be ½ or less, or ¼ or less, or ⅛ or less of the amount that isneeded in order to substitute entirely the ligands coordinated in themetal complex, from the viewpoint of binding controlled numbers of metalcomplexes to each other.

The solvent to be used in this method may be an arbitrary solventcapable of stably maintaining the multiple-metal complex-containingcompound of the invention, for example, an aqueous solvent, or anorganic solvent such as dichloroethane or the like.

(Metal Complex)

The metal complex of the invention is a metal complex in which ligandsare coordinate to one metal atom or a plurality of metal atoms of thesame kind, and at least one of the ligands has an uncoordinatedfunctional group that is not coordinated to a metal atom and that isselected from the group consisting of: —COOH (carboxy group), —COOR⁸(ester group), —CR⁸R⁹—OH (alcohol group), —NR⁸{C(═O)R⁹} (amide group),—NR⁸R⁹ (amine group), —CR⁸═N—R⁹ (imine group), —CO—R⁸ (carbonyl group),—PR⁸R⁹ (phosphine group), —P(═O)R⁸R⁹ (phosphine oxide group),—P(OR⁸)(OR⁹) (phosphite group), —S(═O)₂R⁸ (sulfone group), —S⁺(—O⁻)R⁸(sulfoxide group), —SR⁸ (sulfide group), —CR⁸R⁹—SH (thiol group),—CR⁸R⁹—SR¹⁰ (thioether group), and —CR⁸═R⁹R¹⁰ (ethylene bond) (R⁸ to R¹⁰each independently are hydrogen or a monovalent organic group).

Independently for each of R⁸ to R¹⁰, the organic groups mentioned abovein conjunction with R¹ and R² may be cited as examples.

The ligand of the metal complex of the invention may be a hydrogen groupbound with a functional group of the following functional groups whichis coordinated to a metal atom, or an organic group bound with one ormore of the following functional groups which are coordinated to a metalatom: —COO⁻, —CR¹¹R¹²—O⁻, —NR¹¹⁻, —NR¹¹R¹², —CR¹¹═N—R¹², —CO—R¹¹,—PR¹¹R¹², —P(═O)R¹¹R¹², —P(OR¹¹)(OR¹²), —S(═O)₂R¹¹, —S⁺(—O⁻)R¹¹, —SR¹¹,and —CR¹¹R¹²—S⁻ (R¹¹ and R¹² each independently are hydrogen or amonovalent organic group).

Examples the ligand of the metal complex of the invention include theligands cited above in conjunction with the metal complexes of themultiple-metal complex-containing compound of the invention. Therefore,independently for each of R¹¹ and R²², the organic groups mentionedabove in conjunction with R¹ and R² may be cited as examples.

It is possible that each ligand of the metal complex of the inventionhave only one functional group coordinated to a metal atom.

(Form in which the Metal Complex in Accordance with the Embodiment has aCarboxy Group as an Uncoordinated Functional Group)

In the case where the metal complex in accordance with the embodimenthas a carboxy group as an uncoordinated functional group, a ligand ofthe metal complex may have a carboxy group that is coordinated to ametal atom. For example, the metal complex may be in a form in which theligand having an uncoordinated functional group is a dicarboxylic acidligand and the ligand not having an uncoordinated functional group is anacetic acid ligand.

Therefore, the metal complex may be an octaacetatotetraplatiniim([Pt(CH₃COO)₈]) in which at least one acetic acid ligand (acetatoligand) is substituted with a dicarboxylic acid ligand.

The dicarboxylic acid ligand may be represented by the followingformula:

⁻OOC—R¹³—COOH

(R¹³ is an alkylene group, an alkenylene group, an alkynylene group, anarylene group, an aralkylen group or a bivalent alicyclic group of C₁ toC₃₀, particularly C₁ to C₁₀).

(Form in which the Metal Complex in Accordance with the Embodiment isDicarboxylic Acid-Substituted Octaacetatotetraplatinum)

The metal complex may be represented by the following formula:

(R¹⁴ is an alkylene group, an alkenylene group, an alkynylene group, anarylene group, an aralkylen group or a bivalent alicyclic group of C₁ toC₃₀, particularly C₁ to C₁₀).

R¹⁴ may be, for example, a p-phenylene group.

(Form in which the Metal Complex in Accordance with the Embodiment has aCarbon-Carbon Double Bond as an Uncoordinated Functional Group)

In the case where the metal complex in accordance with the embodimenthas a carbon-carbon double bond as a uncoordinated functional group, aligand of the metal complex may have a carboxy group that is coordinatedto a metal atom. For example, the metal complex may be in a form inwhich the ligand having an uncoordinated functional group is acarboxylic acid ligand that has a carbon-carbon double bond, namely, anunsaturated carboxylic acid, and in which the ligand not having anuncoordinated functional group is an acetic acid ligand.

Therefore, the metal complex may be an octaacetatotetraplatinum([Pt(CH₃COO)₈]) in which at least one acetic acid ligand is substitutedwith a carboxylic acid ligand that has a carbon-carbon double bond.

The carboxylic acid ligand having a carbon-carbon double bond may berepresented by the following formula:

⁻OOC—R¹⁵

(R¹⁵ is an alkenyl group of C₁ to C₃₀, particularly C₁ to C₁₀).

(Form in which the Metal Complex in Accordance with the Embodiment isOctaacetatotetraplatinum Substituted with a Carboxylic Acid that has aCarbon-Carbon Double Bond)

The metal complex of the invention may be represented by the followingformula:

(R¹⁶ is a linear chain or branched chain alkenyl group of C₁ to C₃₀,particularly C₁ to C₁₀).

(Manufacture Method for an Exhaust Gas Purification Catalyst Through theUse of a Metal Complex in Accordance with the Embodiment)

In a manufacture method for an exhaust gas purification catalyst inaccordance with the embodiment, (a) a solution containing a metalcomplex of the invention, particularly a metal complex having, as anucleus, a metal atom that is preferable for use as a catalyst, isprovided, (b) a catalyst support is impregnated with the solution, and(c) the solution is dried and fired.

The catalyst support may be a porous metal oxide support, for example, aporous metal oxide support selected from the group consisting ofalumina, ceria, zirconia, silica, titanic, and combinations thereof.

The drying and firing of the solution containing the metal complex maybe performed in a condition of a temperature and a time that aresufficient to obtain a metal or metal oxide cluster. For example, thedrying may be performed at a temperature of 120 to 250° C. for 1 to 2hours, and then the firing may be performed at a temperature of 400 to600° C. for 1 to 3 hours. The solvent of the solution to be used in thismethod may be an arbitrary solvent that is capable of stably maintainingthe metal complex of the invention, for example, an aqueous solution, oran organic solution such as dichloroethane or the like.

(Manufacture Method for a Multiple-Metal Complex-Containing CompoundThrough the Use of a Metal Complex in Accordance with the Embodimentthat has a Carboxylic Acid Ligand that has a Carbon-Carbon Double Bond)

In a manufacture method for a multiple-metal complex-containing compoundthrough the use of a metal complex in accordance with the embodiment,(a) a metal complex having a carboxylic acid ligand having acarbon-carbon double bond is provided, and (b) the metal complex isdissolved in a solvent, and an alkylidene group of an uncoordinatedcarbon-carbon double bond is substituted through a cross-metathesisreaction of the carbon-carbon double bond.

The cross-metathesis reaction of the carbon-carbon double bond (olefin)is as follows:

R^(a)R^(b)C═CR^(c)R^(d)+R^(e)R^(f)C═CR^(g)R^(h)→R^(a)R^(b)C═CR^(g)R^(h)+R^(c)R^(f)C═CR^(e)R^(d)

(R^(a) to R^(h) each independently are an organic group such as a alkylgroup or the like).

The cross-metathesis reaction and the catalyst to be used in thisreaction are disclosed in, for example, Japanese Patent ApplicationPublication No. JP-A-2004-123925, Japanese Patent ApplicationPublication No. JP-A-2004-043396, and Published Japanese Translation ofPCT Application, JP-T-2004-510699. The catalyst for the cross-metathesisreaction may be a fourth-generation Grubbs catalyst. Therefore, thereaction can be caused to progress under mild conditions.

COMPARATIVE EXAMPLE Synthesis of [Pt₄(CH₃COO)₈]

The synthesis of the compound was performed using a procedure describedin “Jikken Kagaku Kouza (Experimental Chemistry Course)”, 4th ed., Vol.17, p. 452, Maruzen, 1991. That is, the synthesis was performed asfollows. 5 g of K₂PtCl₄ was dissolved in 20 ml of warm water, and 150 mlof glacial acetic acid was added to the solution. At this time, K₂PtCl₄began precipitating. Without minding this, 8 g of silver acetate wasadded. This slurry-like material was refluxed for 3 to 0.4 hours whilebeing stirred by a stirrer. After the material was let to cool, blackprecipitation was filtered out. Through the use of a rotary evaporator,acetic acid was removed by concentrating a brown precipitation as muchas possible. This concentrate was combined with 50 ml of acetonitrile,and the mixture was left standing. The produced precipitation wasfiltered out, and the filtrate was concentrated again. Substantially thesame operation was performed on the concentrate three times. The finalconcentrate was combined with 20 ml of dichloromethane, and wassubjected to adsorption on a silica gel column. The elution wasperformed with dichloromethane-acetonitrile (5:1), and a red extract wascollected and concentrated to obtain a crystal.

(Supporting)

10 g of magnesium oxide (MgO) was dispersed in 200 g of acetone. Whilethis MgO dispersal solution was being stirred, a solution obtained bydissolving 16.1 mg of [Pt₄(CH₃COO)₈] in 100 g of acetone was added. Themixture was stirred for 10 min. When the stirring was stopped, MgOprecipitated and a pale red supernatant was obtained (i.e.,[Pt₄(CH₃COO)₈] did not adsorb to MgO). This mixed solution wasconcentrated and dried by using a rotary evaporator. The dried powderwas fired at 400° C. in air for 1.5 hours. The supported concentrationof Pt was 0.1 wt %.

(TFM Observation of Clusters)

The appearance of the Pt on the MgO prepared by the foregoing method wasobserved by TEM. Using an HD-2000 type electron microscope of Hitachi,STEM images were observed at an acceleration voltage of 200 kV. An STEMimage of Reference Example 1 is shown in FIG. 2. In this image, Ptparticles having a spot diameter of 0.6 nm estimated from the structureof 4-platinum atom clusters can be seen, demonstrating that, by theforegoing technique, 4-platinum atom clusters can be supported on anoxide support.

Example 1 Synthesis of [Pt₄(CH₃COO)₄{o-C₆H₄(COO)(COOH)}₄]

The synthesis of this compound was performed in a scheme shown in FIG.3.

Concretely, this compound was synthesized as follows. After[Pt₄(CH₃COO)₈] (460 mg, 369 μmol) synthesized in the method ofComparative Example and o-C₆H₄(CO₂H)₂ (1.50 g, 9.00 mmol) were placed inan argon-substituted Schlenk device of 50 ml, 10 ml of CH₂Cl₂ and 10 mlof MeOH were added in that order. Immediately, the solution changed intoan orange-red solution. After the solution was stirred at roomtemperature for 2 hours, the solvent was removed by evaporation underreduced pressure, so that a solid was obtained. This solid was dissolvedin CH₂Cl₂, and was filtered. The filtrate was dried under reducedpressure to obtain a yellow solid.

The spectral data of the compound, and results of the elementaryanalysis thereof are shown below.

¹H NMR (300 MHz, CDCl₃, 308K) δ: 1.96 (s, 12H, CH₃), 7:55-7.67 (m, 12H,aromatic H), 8.40-8.43 (m, 4H, aromatic H), 123 (br s′, w_(1/2)=32.4 Hz,4H, —CO₂H).

¹³C{¹H} NMR (75 MHz, CDCl₃, 308K) δ: 21.3 (O₂CCH₃), 126.3, 129.1, 129.8,131.1, 132.1, 135.8 (aromatic C), 176.9 (CO₂H), 180.1 (O₂CCH₃).

IR (KBr disk, ν/cm⁻¹): 1715 (C═O), 1557, 1386 (CO₂ ⁻).

Anal. Calcd. for C₄₀H₃₂O₂₄Pt₄: C, 28.65; H, 1.92. Found: C, 28.63; H,2.15.

(Structural Confirmation of the Compound)

The structure of the compound was determined through the X-ray structureanalysis of the single crystal of the compound obtained in a CH₂Cl₂solution.

(Supporting)

10 g of MgO was dispersed in 200 g of acetone. While this MgO dispersalsolution was being stirred, a solution obtained by dissolving 21.5 mg of[Pt₄(CH₃COO)₄{o-C₆H₄(COO)(COOH)}₄] in 100 g of acetone was added. Thismixture was stirred for 10 min. When the stirring was stopped, MgOprecipitated and the supernatant became transparent (i.e.,[Pt₄(CH₃COO)₄{o-C₆H₄(COO)(COOH)}₄] adsorbed to MgO). This mixed solutionwas concentrated and dried by using a rotary evaporator. The driedpowder was fired at 400° C. in air for 1.5 hours. The supportedconcentration of Pt was 0.1 wt %.

(TEM Observation of Clusters)

The appearance of Pt on MgO prepared in the foregoing method wasobserved by TEM. Using an HD-0.2000 type electron microscope of Hitachi,STEM images were observed at an acceleration voltage of 200 kV. An STEMimage of Example 1 is shown in FIG. 4. In this image, Pt particleshaving a spot diameter of 0.6 nm estimated from the structure of4-platinum atom clusters can be seen, demonstrating that, by theforegoing technique, 4-platinum atom clusters can be supported on anoxide support.

Example 2 Synthesis of[Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH(CH₂)₃CO₂}(CH₃COO)₇Pt₄]

The synthesis of this compound was performed in a scheme shown in FIG. 5and FIG. 6.

Concretely, this compound was synthesized as follows. CH₂═CH(CH₂)₃CO₂H(19.4 μL, 18.6 mg) was added to a CH₂Cl₂ solution (10 mL) of theoctaacetatotetraplatinum [Pt₄(CH₃COO)₈] (0.204 g, 0.163 mmol) obtainedby the procedure shown above in conjunction with Comparative Example 1.This changed the color of the solution from orange to red-orange. Afterthe solution was stirred at room temperature for 2 hours, the solventwas removed by evaporation under reduced pressure, and the remainingsubstance was washed with diethyl ether (8 mL) twice. As a result, anorange solid of [Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH₂}] was obtained.

[Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH₂}] (362 mg, 0.277 mmol) synthesized asdescribed above and a first-generation Grubbs catalyst (6.7 mg, 8.1μmol, 2.9 mol %) were placed in an argon-substituted Schlenk device, andwere dissolved in CH₂Cl₂ (30 mL). A cooling pipe was attached to theSchlenk device, and a heated reflux was performed in an oil bath. Afterthe solution was refluxed for 60 hours, the solvent was removed byevaporation under reduced pressure, and the remaining substance wasdissolved in CH₂Cl₂. After that, filtration via a glass filter wasperformed. The filtrate was concentrated under reduced pressure toobtain a solid. The solid was washed with diethyl ether (10 mL) threetimes to obtain an orange solid of[Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH(CH₂)₃CO₂}(CH₃COO)₇Pt₄] as an E/Z typemixture.

(Spectral Data)

[Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH₂}]

¹H NMR (300 MHz, CDCl₃, 308K) δ: 1.89 (tt, ³J_(HH)=7.5, 7.5 Hz, 2H,O₂CCH₂CH₂—), 1.99 (s, 3H, ^(ax)O₂CCH₃), 2.00 (s, 3H, ^(ax)O₂CCH₃), 2.01(s; 6H, ^(ax)O₂CCH₃), 2.10 (q like, 2H, —CH₂CH═CH₂), 2.44 (s, 6H,^(eq)O₂CCH₃), 2.45 (s, 3H, ^(eq)O₂CCH₃), 2.70 (t, ³J_(EE)=7.5 Hz, 2H,O₂CCH₂CH₂—), 4.96 (ddt, ³J_(HH)=10.4 Hz, ²J_(HH)=1.8 Hz, ⁴J_(HH)=?Hz,1H, —CH═C(H)^(cis)H), 5.01 (ddt, ³J_(HH)=17.3 Hz, ²J_(HH)=1.8 Hz,⁴J_(HH)=?Hz, 1H, —CH═C(H)^(trans)H), 5.81 (ddt, ³J_(HH)=17.3, 10.4, 6.6Hz, 1H, —CH═CH₂).

¹³C{¹H} NMR (75 MHz, CDCl₃, 308K) δ: 21.2, 21.2 (^(ax)O₂CCH₃), 22.0,22.0 (^(eq)O₂CCH₃), 25.8 (O₂CCH₂CH₂—), 33.3 (—CH₂CH═CH₂), 35.5(O₂CCH₂CH₂—), 115.0 (—CH═CH₂), 137.9 (—CH═CH₂), 187.5, 193.0, 193.1(O₂CCH₃), 189.9 (O₂CCH₂CH₂—).

MS (ESI+, CH₃CN solution) m/z: 1347 ([M+sol.]⁴).

IR (KBr disk, ν/cm⁻¹): 2931, 2855 (ν_(C—H)), 1562, 1411 (ν_(COO—)),1039, 917 (ν_(—C═C—)).

(Spectral Data)

[Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH(CH₂)₃CO₂}(CH₃COO)₇Pt₄]

Major (E Type):

¹H NMR (300 MHz, CDCl₃, 308K) δ: 1.83 (like, J=7.7 Hz, 4H, O₂CCH₂CH₂—),2.00 (s, 6H, ^(ax)O₂CCH₃), 2.01 (s, 18H, ^(ax)O₂CCH₃), 2.02-2.10 (m, 4H,—CH₂CH═CH—), 2.44 (s, 18H, ^(eq)O₂CCH₃), 2.67 (t, ³J_(H—H)=7.2 Hz, 4H,O₂CCH₂CH₂—), 5.37-5.45 (m, 2H, —CH═).

¹³C NMR (75 MHz, CDCl₃, 308K) δ: 21.1₇ (q, ¹J_(C—H)=130.9 Hz,^(ax)O₂CCH₃), 21.2₂ (q, ¹J_(C—H)=131.1 Hz, ^(ax)O₂CCH₃), 21.9 (q,¹J_(C—H)=129.4 Hz, ^(eq)O₂CCH₃), 22.0 (q, ¹J_(C—H)=129.4 Hz,^(eq)O₂CCH₃), 26.4 (t, ¹J_(C—H)=127.3 Hz, O₂CCH₂CH₂—), 32.0 (t,¹J_(C—H)=127.3 Hz, —CH₂CH═CH—), 35.5 (t, ¹J_(C—H)=130.2 Hz, O₂CCH₂CH₂—),130.1 (d, ¹J_(C—H)=148.6 Hz, —CH═), 187.3, 187.4, 193.0 (O₂CCH₃), 189.9(O₂CCH₂CH₂—).

Minor (Z Type):

¹H NMR (300 MHz, CDCl₃, 308K) δ: 1.83 (like, J=7.7 Hz, 4H, O₂CCH₂CH₂—),2.00 (s, 6H, ^(ax)O₂CCH₃), 2.01 (s, 18H, ^(ax)O₂CCH₃), 2.02-110 (m, 4H,—CH₂CH═CH—), 2.44 (s, 18H, ^(eq)O₂CCH₃), 2.69 (t, ³J_(H—H)=7.2 Hz, 4H,O₂CCH₂CH₂—), 5.37-5.45 (m, 2H, —CH═).

¹³C NMR (75 MHz, CDCl₃, 308K) δ: 21.1₇ (q, ¹J_(C—H)=130.9 Hz,^(ax)O₂CCH₃), 21.2₂ (q, ¹J_(C—H)=131.1 Hz, ^(ax)O₂CCH₃), 21.9 (q,¹J_(C—H)=129.4 Hz, ^(eq)O₂CCH₃), 22.0 (q, ¹J_(C—H)=129.4 Hz,^(eq)O₂CCH₃), 26.5 (t, ¹J_(C—H)=127.3 Hz, O₂CCH₂CH₂—), 26.7 (t,¹J_(C—H)=127:3 Hz, —CH₂CH═CH—), 35.5 (t, ¹J_(C—H)=130.2 Hz, O₂CCH₂CH₂—),129.5 (d, ¹J_(C—H)=154.3 Hz, —CH═), 187.3, 187.4, 193.0 (O₂CCH₃), 189.9(O₂CCH₂CH₂—).

MS (ESI+, CH₃CN solution) m/z: 2584 ([M]⁺),

(Supporting)

10 g of MgO was dispersed in 200 g of acetone. While this MgO dispersalsolution was being stirred, a solution obtained by dissolving 16.6 mg of[Pt₄(CH₃COO)₇{O₂C(CH₂)₃CH═CH(CH₂)₃CO₂}(CH₃COO)₇Pt₄] in 100 g of acetonewas added. The mixture was stirred for 10 min. This mixed solution wasconcentrated and dried by using a rotary evaporator. The dried powderwas fired at 400° C. in air for 1.5-hours. The supported concentrationof Pt was 0.1 wt %.

(TEM Observation of Clusters)

The appearance of the Pt on the MgO prepared by the foregoing method wasobserved by TEM. Using an HD-2000 type electron microscope of Hitachi,STEM images were observed at an acceleration voltage of 200 kV. An STEMimage of Example 2 is shown in FIG. 7. In this image, Pt particleshaving a spot diameter of 0.9 nm estimated from the structure of8-platinum atom clusters can be seen, demonstrating: that, by theforegoing technique, 8-platinum atom clusters can be supported on anoxide support.

Example 3 Synthesis of [Pt₄(CH₃COO)₇{O₂C(p-C₆H₄)—CO₂}(CH₃COO)₇Pt₄]

The synthesis of this compound was performed in a scheme shown in FIG.8.

Concretely, this compound was synthesized as follows. A CH₂Cl₂ solution(10 mL) of [Pt₄(CH₃COO)₈] (0.204 g, 0.163 mmol) obtained bysubstantially the same procedure as in Comparative Example was combinedwith an amount of terephthalic acid (HO₂C-(p-C₆H₄)—CO₂H) (0.0135 g,0.0815 mmol) that was half the amount of [Pt₄(CH₃COO)₈]. As a result, ablack precipitation was produced. This precipitation was washed twicewith CH₂Cl₂ (10 mL) to obtain crystal of[Pt₄(CH₃COO)₇{O₂C-(p-C₆H₄)—CO₂}(CH₃COO)₇Pt₄].

(Identification)

The compound was identified by elementary analysis since the crystal ofthe compound did not dissolve in solvents. Results were as shown below.

Anal. Calcd. for C₃₆H₄₆O₃₂Pt₈: C, 16.95; H, 1.82. Found: C, 20.10; H,1.78.

While the invention has been described with reference to exemplaryembodiments thereof, it should be understood that the invention is notlimited to the exemplary embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exemplaryembodiments are shown in various combinations and configurations, whichare exemplary, other combinations and configurations, including more,less or only a single element, are also within the spirit and scope ofthe invention.

1. An exhaust gas purification catalyst obtainable by a methodcomprising: providing a solution containing a metal complex in whichcarboxylic acid ligands and at least one dicarboxylic acid ligand arecoordinated to one metal atom or a plurality of metal atoms of the samekind, wherein the at least one dicarboxylic acid ligand has anuncoordinated —COOH functional group that is not coordinated to a metalatom; impregnating a catalyst support with the solution; and drying andfiring the solution.
 2. An exhaust gas purification catalyst accordingto claim 1, wherein each of the carboxylic acid ligands is of formulaRCOO⁻, wherein R is hydrogen, an alkyl group, an alkenyl group, analkynyl group, an aryl group, an aralkyl group or a monovalent alicylicgroup.
 3. An exhaust gas purification catalyst according to claim 2,wherein the carboxylic acid ligand is formate, acetate or propionate. 4.An exhaust gas purification catalyst according to claim 1, wherein theat least one dicarboxylic acid ligand is of formula ⁻OOC—R¹³—COO⁻wherein R¹³ is a bond, an alkylene group, an alkenylene group, analkynylene group, an arylene group, an aralkylene group or a divalentalicylic group.
 5. An exhaust gas purification catalyst according toclaim 1, wherein the carboxylic acid ligands are acetic acid.
 6. Anexhaust gas purification catalyst according to claim 1, wherein themetal is selected from iron, cobalt, nickel, copper, ruthenium, rhodium,palladium, osmium, iridium, platinum, gold and silver.
 7. An exhaust gaspurification catalyst according to claim 6 wherein the metal isplatinum.
 8. An exhaust gas purification catalyst according to claim 1,wherein the metal complex is an octaacetatotetraplatinum in which atleast one acetic acid ligand is substituted with a dicarboxylic acidligand as defined in claim
 1. 9. An exhaust gas purification catalystaccording to claim 1, wherein the metal complex is anoctaacetatotetraplatinum in which at least one acetic acid ligand issubstituted with a dicarboxylic acid ligand as defined in claim
 4. 10.An exhaust gas purification catalyst according to claim 1, wherein themetal complex is represented by a formula below:

wherein R¹⁴ is an alkylene group, an alkenylene group, an alkynylenegroup, an arylene group, an aralkylen group or a bivalent alicylic groupof C₁ to C₃₀.
 11. An exhaust gas purification catalyst according toclaim 1, wherein the catalyst support is a porous metal oxide support.12. A manufacture method for an exhaust gas purification catalyst, whichcomprises: providing a solution containing the metal complex defined inclaim 1, impregnating a catalyst support with the solution; and dryingand firing the solution.
 13. A method according to claim 12, wherein thecatalyst support is a porous metal oxide support.
 14. A metal complex asdefined in claim 1, wherein the metal is platinum.